In an epidemiological investigation of the population of Laredo, Texas, baptism records from the Catholic church have been entered into a dedicted computer through an interactive, on-line system. The errors that occurred in the transcription process have been analyzed by a procedure of triple entry of sampled records. Special attention is paid to the rate and types of error in the entry of personal names. ANOVA and variance component analysis reveals the importance of field and data entry technician for error rates. Some practical suggestions, based on our experience with a large data entry operation, are offered.